1. Field of the Invention
The present invention relates to methods for reducing the gaseous sulfur content of flue gases and, more particularly, but not by way of limitation, to a process for reducing the gaseous sulfur oxide content of flue gases produced by combustion of coal wherein either or both the coal is preheated prior to combustion and the combustion temperature levels are controlled.
2. Brief Description of the Prior Art
Sulfur-containing coals, when ordinarily combusted, produce flue gases which contain sulfur oxides. Because environmental considerations dictate strict limitations on the amount of sulfur oxides which may be released to the atmosphere, considerable attention has been devoted by those skilled in the art to reducing the gaseous sulfur oxide levels in flue gases. Unless gaseous sulfur oxide levels in flue gases are reduced to acceptable levels, the flue gases produced by many types of coal cannot be released to the atmosphere. The prior art has generally focused on reducing sulfur content in flue gases by reducing sulfur oxides either to elemental sulfur or to hydrogen sulfide or by absorbing sulfur oxides in lime-containing scrubbers.